The subject matter disclosed herein relates to magnetic resonance imaging (MRI) compatible headphones. More specifically, headphones suitable for use by a patient in an MRI scanner are disclosed.
As is known to those skilled in the art, an MRI system alternately generates a strong magnetic field and then detects the faint nuclear magnetic resonance (NMR) signals given off by nuclei in the presence of the magnetic field. The NMR signals are received by antennas, also known as coils, and transmitted to the MRI scanner for reconstruction into an MRI image. In order to provide a clear image, it is desirable to minimize electromagnetic interference from outside sources.
As a result, MRI scanners 1 are located within a shielded room 2, also known as the scan room (see FIG. 9). The scan room 2 includes walls, or panels, which typically incorporate RF shielding within the wall. The controller 5 for the MRI scanner 1 is typically located in an adjacent control room 3. A window 4 permits an operator to observe activity within the scan room 2 from the adjacent control room 3. The operator often needs to communicate with the patient, for example, to provide instructions to the patient during the scan. Consequently, a microphone may be provided in the control room for the operator and a headset provided to the patient to receive instructions from the MRI operator.
However, the MRI environment creates numerous challenges that make conventional electronic headsets unusable in the MRI environment. Most commercial headsets utilize a magnetic speaker driver and may include one or more other components that are susceptible to magnetic fields. The magnetic field generated by the MRI scanner may, at a minimum, interfere with these devices, and at worst, pull the devices into the bore of the scanner, potentially injuring the patient. Further, non-magnetic metal components may be susceptible to radio frequency (RF) induced heating. Also, long wire runs, for example, between the control room and the patient or even between earphones function as antennas. These long wire runs raise the potential of both radiating electromagnetic interference detectable by the MRI scanner due to audio signals transmitted on the wire and receiving interference from the MRI scanner which degrades the audio signal provided to the patient.
Historically, these limitations of conventional electronic headsets have been overcome by providing pneumatic headsets to the patient. However, such a system is not without drawbacks. The pneumatic headsets require a dedicated controller to convert an electronic audio signal to a pneumatic audio signal for transmission to the patient. Pneumatic tubing extending from this controller to the patient is also required.